Conversion of hydrocarbons



Patented June .5, 1928.

UNITED STATES P TENT oF'FIca" mun or miswnnr. HILL, ENGLAND, ASSIGNOR or ONE-HALF r nnxm LAING, or HATFIELD, ENGLAND.

CONVERSION 01 HYDROCARBONS.

No Drawing. Original application filed November 27, 1922, Serial No. 603,696, and in Great Britain December 8, 1921. Divided and this application filed March 7, 1925; Serial No. 13,915.

This invention" is a division of my pend- 'ing application Serial No. 603,696, filed No vember 27 1922, and relates to the manufacture and utilizationof formic acid more 5 especially i517 use in connection with the i production or conversion of liquid hydrocarbons, the chief object of the invention to crack of transform liquid hydrocarbons or to obtain an increased yield of lo the more readily liquefiable constituents or condensablehydrocarbons especially during the distillation of carbonaceous materials,

such as coal, lignite, peat, shale, wood and the like. A further object of the invention is to cheapen and simplify the manufacture or production of formic acid.

As is well understood, the amount of liquid or condensable hydrocarbons obtained by destructive orother forms of distillation depends primarily upon the amount of volatile mattercontained in the material to be distilled and secondly upon the term perature. of distillation. ,In distilling processes as at present carried on, only a -percentage of the volatile hydrocarbons containedin the carbonaceous material has been obtained in liquid form, the rest of the volatile hydrocarbons passing oif during the process of distillation in' the form of a so- 80 called permanent gas, that is to say, a gas which cannot be liquefied unless at an exs tremely lowtemperature and under high pressure.

border to increasethe volume of con- 86 densable or liquefiable hydrocarbons yielded up during the process of distillation it has been-proposed toadd to the carbonaceous material before orduring the process of disv tillation certain other materials with the 40 object of exercising a so-called catalytic action thereon, oxidation or hydrogenation being thereby caused to take place in such a way that the relative proportions of the 7 carbon and hydrogen atoms present in the hydrocarbons have been, alteredso as to produce new combinations which give rise to an increased yield of the more readily liquefiable constituents of the hydrocarbons.

One of the'substances which it has been proposed to use for this purpose has been the salts of formic acid, preferably sodium formate, this substance being mixed in various proportions with the carbonaceous maduction terial which is to be distilled and, by its use, a higher proportionate yield of liquid hydrocarbon has been stated to result.

present time, however, these Up to the attempts have mental character and have been more or less'of an-experinot been developed on a commercial scale on account of the fact that the cost which would produce of an active catalyzer oxidization or hydrogenation, or of the sodium formate, was out erably a metal oxide catalyzer, or from carof the -in bon monoxide in the presence of water vapour and a metallic catalyzer.

A gas also suitable for the catalytic proof formic acid consists for instance of co-called air gas, composed principally of carbon monoxide and nitrogen, or ordinary coal gas, containing methane, or natural gas may Zoe used. p

In the case of methane or a gas containing methane-the gas is passed over a suitable metal catalyzer or metallic oxide catalyzer and the following reaction takes place.

In the presence of the catalyzer, the CO combines with the H 0 to produce formic acid (CH O or H.C '0.0H).

The metal oxide catalyze-r which I have found most suitable may be manufactured as follows z-An activated copper sub-oxide is produced by precipitating copper from a solution ofcopper sulphate by means of metallic zinc the copper sulphate being greatly in excess so as to ensure thatno metallic zinc is present. The precipitated copper sub-oxide is thereafter washed and boiled so as to remove as far as possible all traces of zinc and afterwards dried and roasted in the air.. Although I have foundan activated copper sub-oxide produced in the foregoing manner to be satisfactory, other copper oxides precip itated from copper salts (whether organic or inorganic and by any suitable method ineluding Sabatiers method) or ordinary granulated or powdered copper may also be CO,+ E H1" 7 c OHOOH (CHaOs).

the resulting products being therefore as follows I um lime in excess, is carefully cleansed of impurities and conducted overor through the fine spongy granules of an activated copper sub-oxide produced in the foregoing manner. The methane appears to be split up and oxidized in the following manner In the foregoing reaction the. methane takes its oxygen from the copper sub-oxide,

' as no free'oxygen 1s required. The reaction has is an endothermic one and requires a temperature ranging from 250 to 800 centigrade.

When manufacturing formic acid from carbon monoxide or a gas containing carbon monoxide the reaction is carried on in the presenceof water vapour inaddition to the metallic catalyzer. I

Chemical analysis of the activated copper sub-oxide produced in the foregoing manner shows that it appears to a 'proach very closely the formula Cu O be ore acting on'the.

methane or carbon monoxide. After acomparatively short time however, the copper sub-oxide becomes inactive and appears to have lost a certain amount of its oxygen.

, At the same time'it becomes lighter in colour and analysis gives the formula Cu O or Cu .Cu O.. In order to revivify the copper sub-oxide I may moisten the same with a very weak solution of zinc sulphate and roast it in air at a temperature of approximately 100 C. After treatment in the way the copper sub-oxide becomes re-activated and the operation of revivifying the vitiated copper sub-oxide can be repeated over and over agam. Precipitated copper sub-oxide produced as aforesaid retains its activity for a ppolonged period.

Acco ding to a further feature of the present lnvention free formic acid is admitted in vapour form into the interior of a distillaair gas or a gas containing methane or car tion chamber, retort or the like containing carbonaceous materials which are undergoing distillation, the formic acid being referably produced as aforesaid from methane,

bon monoxide by theaid of a suitable catalyst as a step 111 the process of distillation.

The carbonaceous material may contain a small percentage of admixed carbonates of sodium, potassium or calciuln.

The hydrogen liberated during the reaction which results in the production of for-" mic acid, being in the nascent state, is .very

active in promoting new hydrocarbon products, while at the high temperature prevailing within the distillationvchamber or retort, the formic acid is immediately decomposed and further nascent hydrogen is set ree.

The catalytic reaction for the production of formic acid being endothermic, that is to say, requiring heat, the heat can conveniently be supplied by utilizing the so-called sensible or mechanical heat oflthe carbon monoxide or methane itself as it issues from an adjacent producer. After the reaction is completed or carried out to the desired extent, the spent gases, containing free formic acid in the form of vapour, may be injected or admitted to the distillation chamber, retort, or otherchamber containing the carbonaceous material or the hydrocarbons which are being distilled or converted. By'

of carbonaceous materials is carried out in a retort which isheated internallyby means of the sensible heat of producer gas, such .as, for example, air gas as mentioned above described, and utilizing the or water gas,-it ispossible to by-pass into a suitable chamber any convenient amount of such gas in the hot state at which it leaves the producer, and, after the conversion of the whole or part of the carbon monoxide into formic acid, this gas may be allowed to mingle, for the purpose described, with the main supply of gases as they enter the retort, or 1t may be admitted at venient 'point.

It is to be understood that the present process may also be applied to'the conversion of liquid" hydrocarbons, the hydrocarbons to this end being heated in a suitable chamber until they volatilize and the free formic acid being admitted to the said chamber. Other gases of the hydrocarbon series maybe treated with the activated copper sub-oxide, for example, acetylene gas may be converted into formic acid or, in the presence of hydrogen into formaldehyde. The manufacture of acetic acid or the treatment or conversion of other hydrocarbons, industrial gases, or gases containing hydrocarbons, may also be effected by passing the same over an activated copper sub-oxide any other conprepared as aforesaid, as I have found that 4,

produces chemical changes in the said ases. These reactions are endothermic am? the process of treating hydrocarbons of the acetylene type may be carried on at or above a atmospheric pressure and .at a temperature of from 250 to 800 C.

What I claim and desire to secure by Letters Patent of the United States is 1. The process of converting hydrocar- 1U bons while in gaseous form into other compounds which consists in passing the same over a copper sub-oxide while maintaining a temperature of from 250 C. to 800 C.

2. The process of converting hydrocar- 15 bons of the acetylene series into other com- I pounds which consists in passing the same in gaseous condition over an activated copper sub-oxide, while maintaining a temperature of from 250 C. to 800 C,

3. The process of converting hydrocar bons of the acetylene series into other compounds consisting in passing the same in gaseous condition over fine spongy granules of co per sub-oxide having substantially the ormula Cu O while maintaining a temperature of from 250 C. to 800 C. 4. The process of converting hydrocarbons of the acetylene series into higher compounds, which consists in passing the same over an activated copper sub-oxide.

HARALD NIELSEN. 

